The price of apartments in Northern Ireland is seeing double-digit growth as the housing market here continues to improve.

Ulster University's house price index found the average price of a home in the province rose to £147,409 in the first quarter of 2015 - up 5.3% year-on-year.

Meanwhile, house prices in Belfast fell to £148,654 in the first quarter of 2015 from £150,861 last year, driven by dropping prices in south and north Belfast.

The average house price in the first three months of the year in east and west Belfast rose on average price from 2014.

In south Belfast prices fell from an average price of £195,826 in 2014 to £182,806 in 2015. North Belfast followed with prices falling from £97,212 to £95,011.

This is down in part to semi-detached properties not performing as well.

This is the third house price index released this week, after the Office for National Statistics and Department of Finance and Personnel, with all the findings offering different results.

The Residential Property Price Index reported that in quarter one 2015 there was a 6% increase in prices on the previous year, but actually fell by 1% since the last quarter of 2014.

The Office of National Statistics' house price index found the average price was £145,000 in March, up by 7.5% year-on year.

Apartment prices have increased by 11.7% over the last 12 months, rising to £110,545. This is the second consecutive quarter of double digit annual growth for apartments, with prices rising 13.3% in the last three months of 2014.

Lisburn is the area with the highest house prices, where the average price is £181,700, followed by north Down, where the average price is £168,584. The area with the lowest price is Londonderry and Strabane, where the average price is £102,823.

Lead researcher, Professor Stanley McGreal from Ulster University, said: "The most recent findings signal an improvement in the market with more houses being sold at higher prices.

"At a regional level, the overall picture is of price growth with average prices in north Down and Lisburn the highest throughout the region."

Joe Frey, the Housing Executive's head of research, said lower mortgage rates and rising incomes have led to the improving market.

"Ulster University's house price index provides further confirmation that Northern Ireland's housing market has been undergoing a steady recovery over the past two years. Despite this, there has been no significant deterioration in affordability as incomes have started to rise and mortgages interest rates have remained competitive."

Simon Brien, from Simon Brien Residential Estate agents, said the apartment sector was performing very strongly.

"Apartments are selling exceptionally well and people are bidding on them."

Mr Brien pointed out the apartment market was hardest-hit after the property crash, due to speculators driving the prices up during the boom.

Now the demand for apartments is being fuelled by owner-occupier purchases, with prices starting to get back to their pre-boom level.

The three house price surveys released this week produced different results as they all used different methods to calculate house prices.

Ulster University gets its data from estate agents, while the ONS gets its statistics from the Council for Mortgage Lenders. The Department of Finance's results, the only ones which are not a survey, are derived from stamp duty transactions.

Angela McGowan, chief economist from Danske Bank, said the DFP's index is the most reliable as it includes all the sales which took place, because they use data from HM Revenue and Customs.

£147,409: The average cost of a house in Northern Ireland

£181,700: The average price in Ulster's most expensive area to live, Lisburn